Cord reinforced tire fabric is commonly made in a continuous calendering process which results in a sandwich including multiple strands of cord with a layer of rubber on each side. It is essential to the strength of the fabric and the resulting tire that the space between the tire cords not exceed some specified value. The maximum value could be exceeded, for example, if cords are out of position, missing, if the cord diameter varies, or a combination of the preceding. Similarly, it is important that the space between cords not be too small. This is because the rubber latex which makes up the body of the fabric is applied from both sides of the cord core, and it is essential that the latex be able to easily flow between the cords and coalesce into a single mass.
A system which merely counts the number of cords per inch is not satisfactory since such a system gives only the average spacing and cannot detect a single space fault.
The open space (aperture) between tire cords is significant not only because cf its relationship to the strength of the product, but it is also useful in the continuous determination of the basis weight of product as it is being manufactured. One method of determining basis weight involves measuring the amount of beta ray radiation passing through the fabric. Since the cord spacing affects the beta ray transparency of the fabric, a correction to the basis weight calculation from beta ray measurements is required. The present invention provides a signal which can be used for such a correction.